Magnetic devices having perpendicular magnetic tunnel junction

ABSTRACT

Provided are magnetic memory devices with a perpendicular magnetic tunnel junction. The device includes a magnetic tunnel junction including a free layer structure, a pinned layer structure, and a tunnel barrier therebetween. The pinned layer structure may include a first magnetic layer having an intrinsic perpendicular magnetization property, a second magnetic layer having an intrinsic in-plane magnetization property, and an exchange coupling layer interposed between the first and second magnetic layers. The exchange coupling layer may have a thickness maximizing an antiferromagnetic exchange coupling between the first and second magnetic layers, and the second magnetic layer may exhibit a perpendicular magnetization direction, due at least in part to the antiferromagnetic exchange coupling with the first magnetic layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 14/535,315, filed Nov. 6, 2014, which is a continuation of U.S.patent application Ser. No. 13/987,150, filed Jul. 2, 2013, which claimspriority to Korean Patent Application No. 10-2012-0091484, filed Aug.21, 2012, the entire contents of which are hereby incorporated byreference. U.S. patent application Ser. No. 13/987,150 is acontinuation-in-part of, and claims priority under 35 U.S.C. §120 to,U.S. patent application Ser. No. 13/838,598, filed on Mar. 15, 2013, nowabandoned, which is a continuation of U.S. patent application Ser. No.12/862,074, filed on Aug. 24, 2010, which claims priority to KoreanPatent Application No. 10-2009-0086084, filed on Sep. 11, 2009 andKorean Patent Application No. 10-2009-0093306, filed on Sep. 30, 2009,the entire contents of which are hereby incorporated by reference. U.S.patent application Ser. No. 13/987,150 is also a continuation-in-partof, and claims priority under 35 U.S.C. §120 to, U.S. patent applicationSer. No. 13/091,215, filed on Apr. 21, 2011, now U.S. Pat. No.8,476,722, which claims priority to Korean Patent Application No.10-2010-0037017, filed on Apr. 21, 2010, the entire contents of whichare hereby incorporated by reference.

BACKGROUND

Example embodiments of the inventive concept relate to a semiconductordevice, and in particular, to magnetic device such as magnetic memorydevices having a perpendicular magnetic tunnel junction.

With the increasing use of portable computing devices and wirelesscommunication devices, semiconductor devices may require higher density,lower power, and/or nonvolatile properties. Magnetic memory devices maybe able to satisfy the aforementioned technical requirements.

An example data storing mechanism for a magnetic memory device is atunnel magneto resistance (TMR) effect of a magnetic tunnel junction(MTJ). With the TMR effect, the magnetic orientations of the MTJ can becontrolled by spin-torque switching. For example, a magnetic memorydevice with a MTJ have been developed such that an MTJ may have a TMRratio of several hundred to several thousand percent.

SUMMARY

Example embodiments of the inventive concept provide magnetic devicesincluding a perpendicular magnetic tunnel junction.

Other example embodiments of the inventive concept provide magneticdevices having a perpendicular magnetic tunnel junction with a reducedthickness.

Still other example embodiments of the inventive concept providemagnetic devices having a perpendicular magnetic tunnel junctionconfigured to reduce a magnetic interaction between free and pinnedlayers.

In some embodiments, a magnetic device comprises a free layer structure,a pinned layer structure, and a tunnel barrier therebetween, wherein atleast one of the pinned layer structure or the free layer structurecomprises a first magnetic layer having an intrinsic perpendicularmagnetization property, a second magnetic layer having an intrinsicin-plane magnetization property, and an exchange coupling layerinterposed between the first and second magnetic layers. The exchangecoupling layer may have a thickness selected to provide a desirableamount of antiferromagnetic exchange coupling between the first andsecond magnetic layers, such that the second magnetic layer exhibits anextrinsic perpendicular magnetization direction due at least in part tothe antiferromagnetic exchange coupling with the first magnetic layer.

In some embodiments, the amount of antiferromagnetic exchange couplingmay be at least 4,000 Oe.

In some embodiments, a ratio of a saturation magnetization value of thesecond magnetic layer over a saturation magnetization value of the firstmagnetic layer ranges between about 0.6-about 1.5.

In some embodiments, a saturation magnetization value of the firstmagnetic layer is substantially the same as a saturation magnetizationvalue of the second magnetic layer.

In some embodiments, the saturation magnetization value of each of thefirst and second magnetic layer may range from about 600 to 1400 emu/cc.

In some embodiments, the exchange coupling layer is ruthenium, iridium,or rhodium.

In some embodiments, the thickness of the exchange coupling layer isabout 2.5 Å to about 7 Å.

In some embodiments, the thickness of the exchange coupling layer isabout 3 to about 4 Å.

In some embodiments, a thickness of the first magnetic layer ranges fromabout 10 Å to about 80 Å and a thickness of the second magnetic layerranges from about 5 Å to about 20 Å

In some embodiments, a K_(u) value of the first magnetic layer is atleast 3×10⁶ erg. The Ku value is a perpendicular magnetic anisotropicenergy (i.e., magnetic anisotropic energy in the direction perpendicularto the plane of the first magnetic layer).

In some embodiments, the first magnetic layer comprises a single layerof cobalt base alloy.

In some embodiments, the first magnetic layer comprises a multi-layerstack of (Co_(x)/Pt_(y))n. In some embodiments, x/y may range from 0.5to 1.5.

In some embodiments, a magnetic device comprises a magnetic tunneljunction including a free layer structure, a pinned layer structure, anda tunnel barrier therebetween, The pinned layer structure may have afirst magnetic layer having an intrinsic perpendicular magnetizationproperty, a second magnetic layer having an intrinsic in-planemagnetization property, and an exchange coupling layer interposedbetween the first and second magnetic layers. The exchange couplinglayer may have a thickness selected to provide a desirable amount ofantiferromagnetic exchange coupling between the first and secondmagnetic layers, and the second magnetic layer exhibits an extrinsicperpendicular magnetization direction as a result of theantiferromagnetic exchange coupling with the first magnetic layer.

According to example embodiments of the inventive concepts, a magneticdevice may include a magnetic tunnel junction including a free layerstructure, a pinned layer structure, and a tunnel barrier therebetween.The pinned layer structure may include a first magnetic layer having anintrinsic perpendicular magnetization property, a second magnetic layerhaving an intrinsic in-plane magnetization property, and an exchangecoupling layer interposed between the first and second magnetic layers.The exchange coupling layer may have a thickness selected to provide adesirable amount of antiferromagnetic exchange coupling between thefirst and second magnetic layers, and the second magnetic layer mayexhibit an extrinsic perpendicular magnetization direction, as a resultof the antiferromagnetic exchange coupling with the first magneticlayer. An exchange coupling intensity of the magnetic tunnel junctionmay range from about 4,000 to about 10,000 Oe.

In example embodiments, the thickness of the exchange coupling layer maybe selected in such a way that the second magnetic layer can have aperpendicular magnetization antiparallel to a magnetization direction ofthe first magnetic layer.

In example embodiments, the exchange coupling layer may be formed of atleast one of ruthenium, iridium, or rhodium.

In example embodiments, the thickness of the exchange coupling layerranges from about 2.5 Å to about 5.0 Å.

In example embodiments, the first magnetic layer may include at leastone of 1) a single-layer structure made of cobalt-platinum alloy orcobalt-platinum alloy added with an element X, where the element X maybe at least one of boron, ruthenium, chromium, tantalum, or oxide, or 2)a multi-layer structure including cobalt-containing layers and noblemetal layers alternatingly stacked on each other. The cobalt-containinglayers may be formed of one of cobalt, cobalt iron, cobalt nickel, orcobalt chromium, and the noble metal layers may be formed of one ofplatinum and palladium.

In example embodiments, the second magnetic layer may be a single- ordual-layered structure including at least one of Co, CoFeB, CoFeBTa,CoHf, or CoZr.

In example embodiments, the free layer structure may include a freelayer having the intrinsic in-plane magnetization property, and anon-magnetic metal oxide layer inducing a perpendicular magnetizationproperty to the free layer.

In example embodiments, the free layer may be a single- or multi-layerstructure including at least one of Fe, Co, Ni, CoFe, NiFe, NiFeB,CoFeB, CoFeBTa, CoHf, CoFeSiB or CoZr.

In example embodiments, the non-magnetic metal oxide layer may be asingle- or multi-layer structure including at least one of tantalumoxide, magnesium oxide, ruthenium oxide, iridium oxide, platinum oxide,palladium oxide, or titanium oxide and being in direct contact with thefree layer.

In example embodiments, the device may further include a firstconductive element connecting the magnetic tunnel junction to aswitching device, and a second conductive element connecting themagnetic tunnel junction to an interconnection line. The free layerstructure may be interposed between the first conductive element and thetunnel barrier or between the second conductive element and the tunnelbarrier.

According to example embodiments of the inventive concepts, a magneticdevice may include a magnetic tunnel junction including a free layerstructure, a pinned layer structure, and a tunnel barrier therebetween.Each of the free and pinned layer structures may include an in-planelayer having an intrinsic in-plane magnetization property and aperpendicularing layer inducing a perpendicular magnetization propertyto the in-plane layer. The perpendicularing layer of the free layerstructure may include a non-magnetic metal oxide layer, and theperpendicularing layer of the pinned layer structure may include anexchange coupling layer and a perpendicular layer having an intrinsicperpendicular magnetization property. The exchange coupling layer mayhave a thickness selected in such a way that the perpendicular layer andthe in-plane layer of the pinned layer structure may be subjected to anantiferromagnetic exchange coupling therebetween.

In some embodiments, the magnetic device may further include a lowerelectrode, an upper electrode, the magnetic tunnel junction disposedbetween the lower electrode and the upper electrode, and a totalthickness of the magnetic device may be smaller than about 15 nm.

In example embodiments, the exchange coupling layer may be disposedbetween the perpendicular layer and the in-plane layer of the pinnedlayer structure, and the non-magnetic metal oxide layer may be providedto cover directly the in-plane layer of the free layer structure.

In example embodiments, the exchange coupling layer may be formed of atleast one of ruthenium, iridium, or rhodium.

In example embodiments, the exchange coupling layer may have thethickness maximizing the antiferromagnetic exchange coupling between theperpendicular layer and the in-plane layer of the pinned layerstructure.

In example embodiments, the thickness of the exchange coupling layer mayrange from about 2.5 Å to about 5.0 Å.

In example embodiments, the non-magnetic metal oxide layer may be asingle- or multi-layer structure including at least one of tantalumoxide, magnesium oxide, ruthenium oxide, iridium oxide, platinum oxide,palladium oxide, or titanium oxide.

In example embodiments, the perpendicular layer may include at least oneof cobalt-containing perpendicular magnetic materials.

In example embodiments, the perpendicular layer may be formed ofcobalt-platinum alloy or cobalt-platinum alloy added with an element X,where the element X may be at least one of boron, ruthenium, chromium,tantalum, or oxide.

In example embodiments, the perpendicular layer may be a multi-layerstructure including cobalt-containing layers and noble metal layersalternatingly stacked on each other, the cobalt-containing layers may beformed of one of cobalt, cobalt iron, cobalt nickel, and cobaltchromium, and the noble metal layers may be formed of one of platinumand palladium.

In example embodiments, the perpendicular layer may be a dual-layerstructure including a first perpendicular layer and a secondperpendicular layer, and each of the first and second perpendicularlayers comprises: a layer of cobalt-platinum alloy or cobalt-platinumalloy added with an element X, where the element X may be at least oneof boron, ruthenium, chromium, tantalum, or oxide, or a multi-layerstructure including cobalt-containing layers and noble metal layersalternatingly stacked on each other. The cobalt-containing layers may beformed of one of cobalt, cobalt iron, cobalt nickel, and cobaltchromium, and the noble metal layers may be formed of one of platinumand palladium.

In example embodiments, the pinned layer structure may further include acobalt layer or a cobalt-rich layer interposed between the exchangecoupling layer and the perpendicular layer.

In example embodiments, the in-plane layer of the pinned layer structuremay be a single- or multi-layer structure including at least one ofcobalt, iron, or alloys thereof.

In example embodiments, the in-plane layer of the pinned layer structuremay be a multi-layer structure including a pair of magnetic layershaving the intrinsic in-plane magnetization property and a non-magneticmetal layer interposed therebetween.

In example embodiments, the in-plane layer of the pinned layer structuremay be a single- or dual-layer structure including at least one of Co,CoFeB, CoFeBTa, CoHf, CoFeSiB or CoZr.

In example embodiments, the in-plane layer of the free layer structuremay be a single- or multi-layer structure including at least one ofcobalt, iron, nickel, or alloys thereof.

In example embodiments, the in-plane layer of the free layer structuremay be a single- or multi-layer structure including at least one of Fe,Co, Ni, CoFe, NiFe, NiFeB, CoFeB, CoFeBTa, CoHf, CoFeSiB or CoZr.

In example embodiments, the in-plane layer of the free layer structuremay be a multi-layer structure including a pair of magnetic layershaving the intrinsic in-plane magnetization property and a non-magneticmetal layer interposed therebetween. For example, the pair of themagnetic layers may be formed of CoFeB and the non-magnetic metal layermay be a tantalum layer having a thickness of about 2 Å-20 Å.

In example embodiments, the device may further include a firstconductive element connecting the magnetic tunnel junction to aswitching device, and a second conductive element connecting themagnetic tunnel junction to an interconnection line. The secondconductive element may be a single- or multi-layer structure includingat least one of noble metal layers, magnetic alloy layers, or metallayers.

In example embodiments, the free layer structure may be disposed closerto the first conductive element than to the second conductive element,and the pinned layer structure may be disposed closer to the secondconductive element than to the first conductive element.

In example embodiments, the free layer structure may be disposed closerto the second conductive element than to the first conductive element,and the pinned layer structure may be disposed closer to the firstconductive element than to the second conductive element.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments will be more clearly understood from the followingbrief description taken in conjunction with the accompanying drawings.FIGS. 1 through 15 represent non-limiting, example embodiments asdescribed herein.

FIG. 1 is a circuit diagram exemplarily illustrating a unit memory cellof magnetic memory devices according to example embodiments of theinventive concept.

FIGS. 2 through 6 are circuit diagrams exemplarily illustratingselection devices according to example embodiments of the inventiveconcept.

FIG. 7 is a schematic diagram illustrating a first type of a magnetictunnel junction according to example embodiments of the inventiveconcept.

FIG. 8 is a schematic diagram illustrating a second type of a magnetictunnel junction according to example embodiments of the inventiveconcept.

FIG. 9 is a perspective view exemplarily illustrating a free layerstructure constituting a magnetic tunnel junction according to exampleembodiments of the inventive concept.

FIG. 10 is a perspective view exemplarily illustrating a pinned layerstructure constituting a magnetic tunnel junction according to exampleembodiments of the inventive concept.

FIG. 11 is a graph provided to describe some aspects of the inventiveconcept.

FIG. 12 is a sectional view exemplarily illustrating a magnetic tunneljunction according to example embodiments of the inventive concept.

FIG. 13 is a cross-sectional view exemplarily illustrating a magnetictunnel junction according to other example embodiments of the inventiveconcept.

FIG. 14 is a cross-sectional view exemplarily illustrating a magnetictunnel junction according to other example embodiments of the inventiveconcept.

FIG. 15 is a flow chart exemplarily illustrating a method of fabricatinga magnetic device according to some embodiments of the inventiveconcepts.

FIGS. 16 and 17 are block diagrams schematically illustrating electronicdevices including a semiconductor device according to exampleembodiments of the inventive concept.

FIG. 18 is graph provided to describe some aspects of the inventiveconcept.

It should be noted that these figures are intended to illustrate thegeneral characteristics of methods, structure and/or materials utilizedin certain example embodiments and to supplement the written descriptionprovided below. These drawings are not, however, to scale and may notprecisely reflect the precise structural or performance characteristicsof any given embodiment, and should not be interpreted as defining orlimiting the range of values or properties encompassed by exampleembodiments. For example, the relative thicknesses and positioning ofmolecules, layers, regions and/or structural elements may be reduced orexaggerated for clarity. The use of similar or identical referencenumbers in the various drawings is intended to indicate the presence ofa similar or identical element or feature.

DETAILED DESCRIPTION

Example embodiments of the inventive concepts will now be described morefully with reference to the accompanying drawings, in which exampleembodiments are shown. Example embodiments of the inventive conceptsmay, however, be embodied in many different forms and should not beconstrued as being limited to the embodiments set forth herein; rather,these embodiments are provided so that this disclosure will be thoroughand complete, and will fully convey the concept of example embodimentsto those of ordinary skill in the art. In the drawings, the thicknessesof layers and regions are exaggerated for clarity. Like referencenumerals in the drawings denote like elements, and thus theirdescription will be omitted.

It will be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present. Like numbers indicate like elementsthroughout. As used herein the term “and/or” includes any and allcombinations of one or more of the associated listed items. Other wordsused to describe the relationship between elements or layers should beinterpreted in a like fashion (e.g., “between” versus “directlybetween,” “adjacent” versus “directly adjacent,” “on” versus “directlyon”).

It will be understood that, although the terms “first”, “second”, etc.may be used herein to describe various elements, components, regions,layers and/or sections, these elements, components, regions, layersand/or sections should not be limited by these terms. These terms areonly used to distinguish one element, component, region, layer orsection from another element, component, region, layer or section. Thus,a first element, component, region, layer or section discussed belowcould be termed a second element, component, region, layer or sectionwithout departing from the teachings of example embodiments.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the exemplary term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of exampleembodiments. As used herein, the singular forms “a,” “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises”, “comprising”, “includes” and/or “including,” if usedherein, specify the presence of stated features, integers, steps,operations, elements and/or components, but do not preclude the presenceor addition of one or more other features, integers, steps, operations,elements, components and/or groups thereof.

Example embodiments of the inventive concepts are described herein withreference to cross-sectional illustrations that are schematicillustrations of idealized embodiments (and intermediate structures) ofexample embodiments. As such, variations from the shapes of theillustrations as a result, for example, of manufacturing techniquesand/or tolerances, are to be expected. Thus, example embodiments of theinventive concepts should not be construed as limited to the particularshapes of regions illustrated herein but are to include deviations inshapes that result, for example, from manufacturing. For example, animplanted region illustrated as a rectangle may have rounded or curvedfeatures and/or a gradient of implant concentration at its edges ratherthan a binary change from implanted to non-implanted region. Likewise, aburied region formed by implantation may result in some implantation inthe region between the buried region and the surface through which theimplantation takes place. Thus, the regions illustrated in the figuresare schematic in nature and their shapes are not intended to illustratethe actual shape of a region of a device and are not intended to limitthe scope of example embodiments.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which example embodiments of theinventive concepts belong. It will be further understood that terms,such as those defined in commonly-used dictionaries, should beinterpreted as having a meaning that is consistent with their meaning inthe context of the relevant art and will not be interpreted in anidealized or overly formal sense unless expressly so defined herein.

Perpendicular magnetic tunnel junctions and technical features relatedthereto were disclosed in U.S. patent application Ser. Nos. 12/862,074,13/181,957, and 13/398,617, filed on Aug. 24, 2010, Jul. 13, 2011, andFeb. 16, 2012, respectively, the entire contents of which areincorporated as part of this application.

FIG. 1 is a circuit diagram exemplarily illustrating a unit memory cellof magnetic memory devices according to example embodiments of theinventive concept.

Referring to FIG. 1, a unit memory cell UMC may be disposed betweenfirst and second interconnection lines L1 and L2 crossing each other.The unit memory cell UMC may be connected in series to the first andsecond interconnection lines L1 and L2. The unit memory cell UMC mayinclude a selection element SW and a magnetic tunnel junction MTJ. Theselection element SW and the magnetic tunnel junction MTJ may beelectrically connected in series to each other. In example embodiments,one of the first and second interconnection lines L1 and L2 may be usedas a word line, and the other may be used as a bit line.

The selection element SW may be configured to selectively control anelectric current passing through the magnetic tunnel junction MTJ. Forexample, as shown in FIGS. 2 through 6, the selection element SW may beone of a diode, a pnp bipolar transistor, an npn bipolar transistor, anNMOS field effect transistor (FET), and a PMOS FET. If the selectionelement SW is a three-terminal switching device, such as a bipolartransistor and/or MOSFET, an additional interconnection line (not shown)may be connected to the selection element SW.

The magnetic tunnel junction MTJ may include a first magnetic structureMS1, a second magnetic structure MS2, and a tunnel barrier TBRtherebetween. The tunnel bather at TBR may include a non-magneticmaterial. In an embodiment, the tunnel barrier TBR may be formed of aninsulating material layer. Alternatively, the tunnel barrier TBR mayinclude a plurality of layers. For example, the tunnel barrier TBR mayinclude magnesium (Mg), titanium (Ti), aluminum (Al), an oxide ofmagnesium-zinc (MgZn) and/or magnesium-boron (MgB), and/or a nitride oftitanium (Ti) and/or vanadium (V). For example, the tunnel barrier TBRmay be formed of a magnesium oxide (MgO) layer. Each of the first andsecond magnetic structures MS1 and MS2 may include at least one magneticlayer, which is formed of a magnetic material such as a ferromagneticmaterial. In certain embodiments, as shown in FIG. 1, the magnetictunnel junction MTJ may further include a first conductive structureCS1, which may be interposed between the first magnetic structure MS1and the selection device SW, and a second conductive structure CS2,which may be interposed between the second magnetic structure MS2 andthe second interconnection line L2.

One of the magnetic layers of the first and second magnetic structuresMS 1 and MS2 may be configured to have a fixed magnetization direction,which is not changed by a weak external magnetic field generated underusual circumstances. Hereinafter, for convenience in description, a term‘pinned layer PNL’ will be used to represent a magnetic layer having thefixed magnetization property. By contrast, the other of the magneticlayers of the first and second magnetic structures MS1 and MS2 may beconfigured to have a magnetization direction being switchable by angularmomentum from a spin polarized current and/or an external magnetic fieldapplied thereto for its operation. Hereinafter, a term ‘free layer FRL’will be used to represent a magnetic layer having the switchablemagnetization property. That is, as shown in FIGS. 7 and 8, the magnetictunnel junction MTJ may include at least one free layer FRL and at leastone pinned layer PNL, which are separated by the tunnel barrier TBR.

Electrical resistance of the magnetic tunnel junction MTJ may besensitive to a relative orientation of magnetization directions of thefree and pinned layers FRL and PNL. For example, the electricalresistance of the magnetic tunnel junction MTJ may be much greater whenthe relative magnetic orientation between the free and pinned layers FRLand PNL is antiparallel than when parallel. Thus, the electricalresistance of the magnetic tunnel junction MTJ may be controlled bychanging the magnetization direction of the free layer FRL, and thisdifference in the electrical resistance can be used as a data storingmechanism for the magnetic memory devices according to exampleembodiments of the inventive concept.

As shown in FIGS. 7 and 8, the first and second magnetic structures MS1and MS2 of the magnetic tunnel junction MTJ may be sequentially formedon a substrate SUB. The substrate SUB may be a semiconductor substrate.The substrate SUB may include a conductive region and/or an insulatingregion. In example embodiments, according to a relative position betweenthe free layer FRL and the substrate SUB or a stacking order of the freelayer FRL and the pinned layer PNL, the magnetic tunnel junction MTJ maybe, for example, classified into two types: (a) a first type of magnetictunnel junction MTJ1 where the first and second magnetic structures MS1and MS2 include the pinned layer PNL and the free layer FRL,respectively, as shown in FIG. 7, and (b) a second type of magnetictunnel junction MTJ2 where the first and second magnetic structures MS1and MS2 include the free layer FRL and the pinned layer PNL,respectively, as shown in FIG. 8.

According to some aspects of the inventive concept, one of the first andsecond magnetic structures MS1 and MS2 may be a free layer structure FLSto be described with reference to FIG. 9, and the other may be a pinnedlayer structure PLS to be described with reference to FIG. 10. The freelayer structure FLS may be a multi-layer magnetic structure includingthe free layer FRL, and the pinned layer structure PLS may be amulti-layer magnetic structure including the pinned layer PNL.

FIG. 9 is a perspective view exemplarily illustrating a free layerstructure constituting a magnetic tunnel junction according to exampleembodiments of the inventive concept.

According to certain embodiments, the free layer structure FLS mayinclude a free layer FRL and a perpendicular magnetization inducinglayer PMI covering the free layer FRL, as shown in FIG. 9. The freelayer structure FLS may be used as one of the first or second magneticstructures MS1 or MS2.

The free layer FRL may be formed of a magnetic material exhibiting anintrinsic in-plane magnetization property (hereinafter, referred as toan “in-plane magnetic material”). Here, the intrinsic in-planemagnetization property means that a magnetization direction of amagnetic layer is oriented parallel to a longitudinal direction thereof,when there is no external factor applied thereto. For example, if amagnetic layer is provided in a thin film form, whose thickness (e.g., az-directional length) is relatively smaller than its horizontal widths(e.g., x- and y-directional lengths), the magnetic layer having theintrinsic in-plane magnetization property may have a magnetizationdirection parallel to a xy-plane. The “intrinsic in-plane magnetizationproperty”, as will be used below, refers to the in-plane magnetizationof a magnetic layer, which may be found in the absence of the externalfactor.

According to certain embodiments, for the free layer FRL, the intrinsicin-plane magnetization property may be realized by a single- ormulti-layer structure including at least one of a cobalt, iron, nickel,or alloys thereof. For example, the free layer FRL may be a single- ormulti-layer structure including at least one of a Fe, Co, Ni, CoFe,NiFe, NiFeB, CoFeB, CoFeBTa, CoHf, CoFeSiB or CoZr. In certainembodiments, the free layer FRL may be a multi-layered structureincluding a Fe layer, CoHf layer and CoFeB layer. The intrinsic in-planemagnetization materials for the free layer FRL are exemplarily describedin order to provide better understanding of the inventive concept, butexample embodiments of the inventive concepts may not be limitedthereto. The free layer FRL may have a thickness ranging from about 6 Åto about 30 Å or, in certain embodiments, from about 10 Å to about 20 Å.

In certain embodiments, the free layer FRL may be provided in the formof a multi-layered structure including a pair of magnetic layers havingthe intrinsic in-plane magnetization property and a non-magnetic metallayer interposed therebetween. For example, the free layer FRL mayinclude two layers made of a cobalt-iron-boron (CoFeB) alloy and atantalum layer interposed therebetween. The tantalum layer in the freelayer FRL may be formed to have a thickness of about 2 Å-20 Å.

The perpendicular magnetization inducing layer PMI may be in directcontact with the free layer FRL, and as the result of this directcontact, the magnetization direction of the free layer FRL may bechanged to be substantially parallel to the thickness direction (forexample, z direction) of the free layer FRL. In other words, theperpendicular magnetization inducing layer PMI may be an external factorallowing the free layer FRL having the intrinsic in-plane magnetizationproperty to exhibit the perpendicular magnetization direction. In thisrespect, the perpendicular magnetization inducing layer PMI and the freelayer FRL in contact with each other may constitute a structureexhibiting an extrinsic perpendicular magnetization property(hereinafter, referred to as an extrinsic perpendicular structure).

To realize the technical feature, the perpendicular magnetizationinducing layer PMI may be formed of a material capable of inducing astress on a surface of the free layer FRL being in contact therewith. Inthis sense, hereinafter, the perpendicular magnetization inducing layerPMI may be referred to as a ‘stress-inducing layer’ or a ‘contactperpendicularing layer.’ For example, the perpendicular magnetizationinducing layer PMI may be formed of an oxygen-containing material.Alternatively, the perpendicular magnetization inducing layer PMI may beat least one of non-magnetic metal oxides. For example, theperpendicular magnetization inducing layer PMI may be provided in theform of a single- or multi-layered structure including at least one oftantalum oxide, magnesium oxide, ruthenium oxide, iridium oxide,platinum oxide, palladium oxide, titanium oxide, aluminum oxide,magnesium zinc oxide, hafnium oxide, or magnesium boron oxide. Thematerials having the stress-inducing property or the contactperpendicularing property are exemplarily described in order to providea better understanding of the inventive concept, but the inventiveconcepts are not limited thereto.

If the perpendicular magnetization inducing layer PMI is formed of atleast one of the non-magnetic metal oxides, the perpendicularmagnetization inducing layer PMI may have electric resistivity higherthan that of the free layer FRL. This means that electrical resistanceof the magnetic tunnel junction MTJ may be strongly dependent on that ofthe perpendicular magnetization inducing layer PMI. To reduce thisdependence, the perpendicular magnetization inducing layer PMI may beformed to have a thin structure. For example, the perpendicularmagnetization inducing layer PMI may be thinner than the free layer FRL.In example embodiments, the perpendicular magnetization inducing layerPMI may have a thickness ranging from about 3 Å to about 10 Å or, incertain embodiments, from about 4 Å to about 6 Å.

FIG. 10 is a perspective view exemplarily illustrating a pinned layerstructure constituting a magnetic tunnel junction according to exampleembodiments of the inventive concept.

According to certain embodiments, the pinned layer structure PLS mayinclude a first pinned layer (or first magnetic layer) PL1, a secondpinned layer (or second magnetic layer) PL2, and an exchange couplinglayer ECL interposed therebetween, as shown in FIG. 10. The pinned layerstructure PLS may constitute one of the first and second magneticstructures MS1 and MS2.

The first pinned layer PL1 may be formed of a magnetic materialexhibiting an intrinsic perpendicular magnetization property(hereinafter, referred to as a perpendicular magnetic material). Here,the intrinsic perpendicular magnetization property means that amagnetization direction of a magnetic layer is oriented substantiallyparallel to a thickness direction thereof, when there is no externalfactor applied thereto. For example, if a magnetic layer is provided ina thin film form, whose thickness (e.g., the z-directional length) isrelatively smaller than its horizontal widths (e.g., the x- andy-directional lengths), the magnetic layer having the intrinsicperpendicular magnetization property may have a magnetization directionperpendicular to the xy-plane. The “intrinsic perpendicularmagnetization property”, as it will be referred to below, refers to theperpendicular magnetization of a magnetic layer, which may be found inthe absence of the external factor.

According to certain embodiments, for the first pinned layer PL1, theintrinsic perpendicular magnetization property may be realized by asingle- or multi-layered structure including cobalt-containingperpendicular magnetic materials.

In certain embodiments, the first pinned layer PL1 may be a single- ormulti-layered structure including a cobalt-platinum alloy orcobalt-platinum alloys added with an element X, where the element X isat least one of boron, ruthenium, chromium, tantalum, or oxide. In otherembodiments, the first pinned layer PL1 may be provided in the form of amulti-layered structure including cobalt-containing layers and noblemetal layers alternatingly stacked on each other. The cobalt-containinglayers may comprise cobalt, cobalt iron, cobalt nickel, cobalt chromium,or combinations thereof, and the noble metal layers may compriseplatinum, palladium or combinations thereof. In still other embodiments,the first pinned layer PL1 may be provided in the form of amulti-layered structure including at least one of the materials (e.g.,the cobalt-platinum alloy or cobalt-platinum alloys added with anelement X) enumerated above with respect to certain embodiments and atleast one of the materials (e.g., cobalt, cobalt iron, cobalt nickel,cobalt chromium, platinum, and palladium) enumerated in the otherembodiments are provided. In some embodiments, the first pinned layerPL1 may have a thickness ranging from about 10 Å to about 80 Å or, fromabout 30 Å to about 55 Å.

The intrinsic perpendicular magnetization materials for the first pinnedlayer PL1 are exemplarily described in order to provide a betterunderstanding of the inventive concept, but the inventive concepts arenot limited thereto. For example, the first pinned layer PL1 may includeat least one of a) CoFeTb, in which the relative content of Tb is 10% ormore, b) CoFeGd, in which the relative content of Gd is 10% or more, c)CoFeDy, d) FePt with the L1 ₀ structure, e) FePd with the L1 ₀structure, f) CoPd with the L1 ₀ structure, g) CoPt with the L1 ₀structure, h) CoPt with the hexagonal close packing (HCP) structure, i)alloys containing at least one of materials presented in items of a) toh), or j) a multi-layered structure including magnetic and non-magneticlayers alternatingly stacked. The multi-layered structure including thealternatingly-stacked magnetic and non-magnetic layers may include atleast one of (Co/Pt)n, (CoFe/Pt)n, (CoFe/Pd)n, (CoP)n, (Co/Ni)n,(CoNi/Pt)n, (CoCr/Pt)n, or (CoCr/Pd)n, where the subscript n denotes thestacking number. In certain embodiments, the first pinned layer PL1 mayfurther include a cobalt layer or a cobalt-rich layer to be in contactwith the exchange coupling layer ECL.

By contrast, the second pinned layer PL2 may be formed of a magneticmaterial exhibiting the intrinsic in-plane magnetization property (i.e.,the in-plane magnetic material). In other words, the second pinned layerPL2 may have a magnetization direction oriented substantially parallelto a largest surface (e.g., the xy plane) thereof, when there is noexternal factor applied thereto.

For the second pinned layer PL2, the intrinsic in-plane magnetizationproperty may be realized by a single- or multi-layered structureincluding at least one of cobalt, iron, or alloys thereof. For example,the second pinned layer PL2 may be a single- or multi-layered structureincluding at least one of CoFeB, CoFeBTa, CoHf, Co, CoFeSiB or CoZr. Inexample embodiments, the second pinned layer PL2 may be provided in theform of a dual-layered structure including a Co layer and a CoHf layeror a dual-layered structure including a CoFeBTa layer and a CoFeB layer.

In other example embodiments, the second pinned layer PL2 may beprovided in the form of a multi-layered structure including a pair ofmagnetic layers having the intrinsic in-plane magnetization property anda non-magnetic metal layer interposed therebetween. For example, thesecond pinned layer PL2 may include two layers made of acobalt-iron-boron (CoFeB) alloy and a tantalum layer interposedtherebetween.

The intrinsic in-plane magnetization materials for the second pinnedlayer PL2 are exemplarily described in order to provide a betterunderstanding of the inventive concepts, but the inventive concepts arenot limited thereto. In certain embodiments, the second pinned layer PL2may have a thickness ranging from about 5 Å to about 20 Å or, from about10 Å to about 17 Å.

The exchange coupling layer ECL may comprise ruthenium, iridium, rhodiumor combinations thereof. According to example embodiments of theinventive concept, as a result of an antiferromagnetic exchange couplingbetween the first and second pinned layers PL1 and PL2, the secondpinned layer PL2 may have a magnetization substantially parallel to athickness direction thereof. In other words, the exchange coupling layerECL and the first pinned layer PL1 may provide an external factorallowing the second pinned layer PL2 having the intrinsic in-planemagnetization property to exhibit the perpendicular magnetizationdirection. In this respect, the first and second pinned layers PL1 andPL2 and the exchange coupling layer ECL therebetween may constitute anextrinsic perpendicular structure, whose perpendicular magnetizationresults from the antiferromagnetic exchange coupling.

The exchange coupling layer ECL may have a thickness selected in such away that the second pinned layer PL2 can have a perpendicularmagnetization antiparallel to that of the first pinned layer PL1.Furthermore, the exchange coupling layer ECL may have a thicknessselected in such a way that the antiferromagnetic exchange couplingbetween the first and second pinned layers PL1 and PL2 can be maximized.As will be described with reference to FIG. 11, through experimentation,it was found that providing an exchange coupling layer ECL having athickness ranging from about 2.5 Å to about 5.0 Å or, in certainembodiments, from about 3 Å to about 4 Å, was beneficial and exhibitsunexpected results, especially when an annealing process during thefabrication of magnetic devices is under 300° C. However, the exchangecoupling layer ECL may have a thickness ranging from about 2.5 Å toabout 7.5 Å in certain process conditions, for example, when the annealprocess is performed over 300° C. The thickness of the exchange couplinglayer ECL may be increased when the annealing process is performed over300° C. due to the interdiffusion or intermixing of the constituentmagnetic layers.

In some embodiments, various magnetic layers to form the magnetic deviceof the present disclosure may be formed of COFeSiB.

FIG. 11 is a graph provided to describe some aspects of the inventiveconcepts. In particular, FIG. 11 is a graph illustrating a dependence ofa magnetic field intensity Hex of the exchange coupling on a thickness Tof the exchange coupling layer, which was obtained from samplesincluding the pinned layer structure PLS described with reference toFIG. 10. A negative Hex means that the system is in theantiferromagnetic coupling state.

Referring to FIG. 11, the exchange coupling intensity Hex had localminimums near 3.5 Å and 7 Å and had local maximum near 5.5 Å. In otherwords, the exchange coupling intensity Hex was about −5000oe at 7 Å,about −2000oe at 5.5 Å, and about −13000oe at 3.5 Å. Here, the exchangecoupling intensity Hex was smaller than that (i.e., −5000oe) at 3.5 Å,when the exchange coupling layer has a thickness T ranging from 2.5 Å to5.0 Å or from 3 Å to 4 Å.

In other words, when the thickness T of the exchange coupling layer isin a range between about 2.5 Å and about 5.0 Å, or more specificallybetween about 3 Å and about 4 Å, the exchange coupling intensity Hex hada global minimum. This means that, for this embodiment, when theexchange coupling layer has the thickness range (e.g., between about 2.5Å and about 5.0 Å, or more narrowly between about 3 Å and about 4 Å),the pinned layer structure PLS can exhibit a maximized antiferromagneticcoupling effect. It should also be noted, however, that the interactionwith the tunnel barrier layer can further affect the antiferromagneticcoupling effect of the pinned layer structure PLS.

In some embodiments, the embodiments of the present disclosure may setthe thickness of the exchange coupling layer corresponding to a firstpeak of Ruderman-Kittel-Kasuya-Yosida (RKKY) coupling shown in FIG. 11.

FIG. 12 is a cross-sectional view exemplarily illustrating a magnetictunnel junction according to example embodiments of the inventiveconcepts, and FIG. 13 is a cross-sectional view exemplarily illustratinga magnetic tunnel junction according to other example embodiments of theinventive concepts.

Referring to FIG. 12, the pinned layer structure PLS, the tunnel barrierTBR, and the free layer structure FLS may be sequentially stacked on thesubstrate SUB. In other words, the free layer structure FLS and thepinned layer structure PLS may be configured to form the first type ofthe magnetic tunnel junction MTJ1 that was previously described withreference to FIG. 7.

According to the present embodiment, the first conductive structure CS1may be disposed between the first type of the magnetic tunnel junctionMTJ1 and the substrate SUB, and the second conductive structure CS2 maybe provided on the first type of the magnetic tunnel junction MTJ1. Incertain embodiments, the first conductive structure CS1 may serve as aseed layer for forming the first type of the magnetic tunnel junctionMTJ1, and/or as an interconnection pattern or an electrode electricallyconnecting the selection device SW to the first type of the magnetictunnel junction MTJ1. The second conductive structure CS2 may serve as acapping layer covering the first type of the magnetic tunnel junctionMTJ1, and/or as an interconnection pattern or an electrode electricallyconnecting the first type of the magnetic tunnel junction MTJ1 and thesecond interconnection line L2.

In certain embodiments, the first conductive structure CS1 may includethe first conductive layer CL1 and the second conductive layer CL2sequentially stacked on the substrate SUB. The first conductive layerCL1 may be a CoHf layer or a Ta layer having a thickness of about 20 Å,and the second conductive layer CL2 may be a ruthenium layer having athickness of about 40 Å. The materials for the first and secondconductive layers CL1 and CL2 are exemplarily described in order toprovide a better understanding of the inventive concepts, but theinventive concepts are not limited thereto.

The second conductive structure CS2 may be formed to cover theperpendicular magnetization inducing layer PMI, and be provided in theform of a single- or multi-layered structure including at least one ofnoble metal layers, magnetic alloy layers, or metal layers. For example,the noble metal layer for the second conductive structure CS2 may beformed of at least one of Ru, Pt, Pd, Rh, or Ir and the magnetic alloylayer may include at least one of Co, Fe, or Ni, and the metal layer maybe formed of Ta or Ti. The materials for the second conductive structureCS2 are exemplarily described in order to provide a better understandingof the inventive concepts, but the inventive concepts are not limitedthereto.

Referring to FIG. 13, the free layer structure FLS, the tunnel barrierTBR, and the pinned layer structure PLS may be sequentially stacked onthe substrate SUB. In other words, the free layer structure FLS and thepinned layer structure PLS may be configured to form the second type ofthe magnetic tunnel junction MTJ2 that was previously described withreference to FIG. 8.

According to the present embodiment, the free layer structure FLS andthe pinned layer structure PLS may be configured in such a way that bothof the free layer FRL and the second pinned layer PL2 covers the tunnelbarrier TBR. Further, the first conductive structure CS1 may be providedbetween the second type of the magnetic tunnel junction MTJ2 and thesubstrate SUB, and the second conductive structure CS2 may be providedon the second type of the magnetic tunnel junction MTJ2. In someembodiments, the first conductive structure CS1 may serve as a seedlayer for forming the second type of the magnetic tunnel junction MTJ2,and/or as an interconnection pattern or an electrode electricallyconnecting the selection device SW to the second type of the magnetictunnel junction MTJ2. The second conductive structure CS2 may serve as acapping layer covering the second type of the magnetic tunnel junctionMTJ2, and/or as an interconnection pattern or an electrode electricallyconnecting the second type of the magnetic tunnel junction MTJ2 and thesecond interconnection line L2.

In some embodiments, the first conductive structure CS1 may include thefirst conductive layer CL1 and the second conductive layer CL2, whichmay be sequentially stacked on the substrate SUB. The second conductivelayer CL2 may be formed to cover the perpendicular magnetizationinducing layer PMI, and be provided in the form of a single- ormulti-layered structure including at least one of noble metal layers,magnetic alloy layers, or metal layers. The materials for the firstconductive structure CS1 are exemplarily described in order to provide abetter understanding of the inventive concepts, but the inventiveconcepts are not limited thereto.

In some embodiment, as shown in FIG. 14, a magnetic device 140 maycomprise a free layer structure FLS, a pinned layer structure PLS, and atunnel barrier TBR therebetween. The pinned layer structure PLS maycomprise a first magnetic layer PL1 having an intrinsic perpendicularmagnetization property, a second magnetic layer PL2 having an intrinsicin-plane magnetization property, and an exchange coupling layer ECLinterposed between the first and second magnetic layers PL1, PL2. Theexchange coupling layer ECL may have a thickness selected to provide adesirable or maximum amount of antiferromagnetic exchange couplingbetween the first and second magnetic layers PL1 and PL2, such that thesecond magnetic layer PL2 exhibits an extrinsic perpendicularmagnetization direction due at least in part to the antiferromagneticexchange coupling with the first magnetic layer PL1. The amount ofantiferromagnetic exchange coupling may be at least 4,000 Oe.

In some embodiments, the free layer structure FLS may not include a PMIlayer discussed in connection with FIGS. 12 and 13.

In some embodiments, a ratio of a saturation magnetization value of thefirst magnetic layer PL1 with respect to a saturation magnetizationvalue of the second magnetic layer PL2 ranges between about 0.6-about1.5.

In some embodiments, a saturation magnetization value of the firstmagnetic layer PL1 is substantially the same as a saturationmagnetization value of the second magnetic layer PL2. For example, thesaturation magnetization value of each of the first and second magneticlayers PL1, PL2 may range from about 600 to 1400 emu/cc.

In some embodiments, the exchange coupling layer ECL may be, forexample, ruthenium, iridium, or rhodium. In some embodiments, thethickness of the exchange coupling layer ECL is about 3 Å to about 4 Å.

In some embodiments, a thickness of the first magnetic layer (or firstpinned layer) PL1 ranges from about 10 Å to about 80 Å and a thicknessof the second magnetic layer (or second pinned layer) PL2 ranges fromabout 5 Å to about 20 Å

In some embodiments, a K_(u) value of the first magnetic layer PL1 is atleast 3×10⁶ erg. The Ku value is a perpendicular magnetic anisotropicenergy magnetic anisotropic energy in the direction perpendicular to theplane of the first magnetic layer PL1).

In some embodiments, the first magnetic layer PL1 may comprise a singlelayer of cobalt base alloy. In some embodiments, the first magneticlayer PL1 may comprise a multi-layer stack of (Co_(x)/Pt_(y))n. In someembodiments, x/y ranges from 0.5 to 1.5.

In some embodiments, a magnetic device comprises a magnetic tunneljunction including a free layer structure, a pinned layer structure, anda tunnel barrier therebetween, The pinned layer structure may have afirst magnetic layer having an intrinsic perpendicular magnetizationproperty, a second magnetic layer having an intrinsic in-planemagnetization property, and an exchange coupling layer interposedbetween the first and second magnetic layers. The exchange couplinglayer may have a thickness selected to provide a desirable amount ofantiferromagnetic exchange coupling between the first and secondmagnetic layers, and the second magnetic layer exhibits an extrinsicperpendicular magnetization direction as a result of theantiferromagnetic exchange coupling with the first magnetic layer. Thethickness of the exchange coupling layer may range from about 2.5 Å toabout 7.0 Å.

In some other embodiments, although not illustrated, the free layerstructure FLS may include another first magnetic layer similar to thefirst magnetic layer PL1 having an intrinsic perpendicular magnetizationproperty, another second magnetic layer similar to the second magneticlayer PL2 having an intrinsic in-plane magnetization property, andanother exchange coupling layer similar to the exchange coupling layerECL interposed between the first and second magnetic layers PL1 and PL2.In one embodiment, in this case, the pinned layer structure PLS may nothave the exchange coupling layer ECL sandwiched between the first andsecond magnetic layers as discussed above.

In some embodiments, both the free layer structure FLS and the pinnedlayer structure PLS may have the above described first and secondmagnetic layer structures PL1, PL2 having the exchange coupling layerECL disposed therebetween.

In the other magnetic device structures, the separation (ΔH_(sw))between the coercivity of the free layer and the coercivity of thepinned layer may not be sufficient and the hysteresis loop of the freelayer may not be symmetrical, making it nearly impossible to write datainto memory cells. Further, if the stack height is greater than 30 nm,there is a difficulty in achieving higher integration of magneticdevices. In some cases, the hysteresis loop of the free layer and thepinned layer may undesirably overlaps, substantially reducing theswitching probability and switching stability. Additionally, if thestack height is greater than 30 nm, there may be a difficulty inachieving higher integration of magnetic devices.

However, with some or all of the features described above, the freelayer of the magnetic device of the present disclosure can have asymmetrical hysteresis loop and there can be large separation betweenthe coercivity of the pinned layer and the coercivity of the free layer,thus significantly improving the writing probability and the switchingstability.

Although the above described effects of the present disclosure may beobtained utilizing other embodiments or other combinations of the abovedescribed inventive features, inventors of the present disclosure havediscovered that such inventive effects may be exceptional, for example,by forming a magnetic tunnel junction device including the pinned layerthat comprises a first magnetic layer having an intrinsic perpendicularmagnetization property, a second magnetic layer having an intrinsicin-plane magnetization property, and an exchange coupling layerinterposed between the first and second magnetic layers, where theexchange coupling layer has a thickness selected to provide a desirableamount of antiferromagnetic exchange coupling between the first andsecond magnetic layers, such that the second magnetic layer exhibits anextrinsic perpendicular magnetization direction due at least in part tothe antiferromagnetic exchange coupling with the first magnetic layer,the amount of antiferromagnetic exchange coupling being at least 4,000Oe, where the magnetization value of the first magnetic layer issubstantially the same as a saturation magnetization value of the secondmagnetic layer, where the exchange coupling layer is ruthenium, iridium,or rhodium, where the thickness of the exchange coupling layer is about3 Å to about 4 Å, where the second magnetic layer comprises a singlelayer of cobalt base alloy or a multi-layer stack of ((Co_(x)/Pt_(y))n,where x is a thickness of a Co layer and y is a thickness of a Pt layer.

FIG. 15 is a flow chart exemplarily illustrating a method of fabricatinga magnetic device according to some embodiments of the inventiveconcepts.

Referring to FIG. 15, a bottom electrode BL may be formed on a substrateSUB in step S1. A first magnetic layer PL1 having an intrinsicperpendicular magnetization property, an exchange coupling layer ECL,and a second magnetic layer PL2 having an intrinsic in-planemagnetization property are sequentially formed to form a pinned layerstructure PLS on the bottom electrode BL in step S2. The thickness ofthe exchange coupling layer is selected to provide a desirable amount ofantiferromagnetic exchange coupling between the first and secondmagnetic layers such that the second magnetic layer exhibits anextrinsic perpendicular magnetization direction due at least in part tothe antiferromagnetic exchange coupling with the first magnetic layer. Asaturation magnetization value of the first magnetic layer PL1 may besubstantially the same as a saturation magnetization value of the secondmagnetic layer PL2. The amount of antiferromagnetic exchange couplingmay be at least about 4,000 Oe. For example, the amount ofantiferromagnetic exchange coupling may range from about 4,000 Oe to10,000 Oe. The exchange coupling layer may be ruthenium, iridium, orrhodium, where the thickness of the exchange coupling layer may be about3 Å to about 4 Å, and where the second magnetic layer may comprise asingle layer of cobalt base alloy. Alternatively, the second magneticlayer may be formed by depositing a multi-layer stack of(Co_(x)/Pt_(y))n, where x is a thickness of a Co layer and y is athickness of a Pt layer. In Step S3, a tunnel barrier TBR may be formedon the pinned layer structure PLS. In Step S4, a free layer structureFLS is formed on the tunnel bather TBR. In step S5, an upper electrodeUL is formed over the free layer structure FLS to form a magneticdevice.

Also, a total thickness (stack height) of the magnetic device, e.g.,lower and the upper electrodes and the magnetic tunnel junction disposedtherebetween, can be equal to or smaller than about 15 nm Thus, withsome embodiments of present disclosure, almost 50% reduction of the MTJdevice thickness has been made possible. As a result, further scalingdown of the magnetic device can be realized.

FIGS. 16 and 17 are block diagrams schematically illustrating electronicdevices including a semiconductor device according to exampleembodiments of the inventive concept.

Referring to FIG. 16, an electronic device 1300 including asemiconductor device according to example embodiments of the inventiveconcept may be used in one of a personal digital assistant (PDA), alaptop computer, a mobile computer, a web tablet, a wireless phone, acell phone, a digital music player, a wire or wireless electronicdevice, or a complex electronic device including at least two onesthereof. The electronic device 1300 may include a controller 1310, aninput/output device 1320 such as a keypad, a keyboard, a display, amemory 1330, and a wireless interface 1340 that are combined to eachother through a bus 1350. The controller 1310 may include, for example,at least one microprocessor, a digital signal process, a microcontrolleror the like. The memory 1330 may be configured to store a command codeto be used by the controller 1310 or a user data. The memory 1330 mayinclude a semiconductor device according to example embodiments of theinventive concept. The electronic device 1300 may use a wirelessinterface 1340 configured to transmit data to or receive data from awireless communication network using a RF signal. The wireless interface1340 may include, for example, an antenna, a wireless transceiver and soon. The electronic system 1300 may be used in a communication interfaceprotocol of a communication system such as CDMA, GSM, NADC, E-TDMA,WCDMA, CDMA2000, Wi-Fi, Muni Wi-Fi, Bluetooth, DECT, Wireless USB,Flash-OFDM, IEEE 802.20, GPRS, iBurst, WiBro, WiMAX, WiMAX-Advanced,UMTS-TDD, HSPA, EVDO, LTE-Advanced, MMDS, and so forth.

Referring to FIG. 17, a memory system including a semiconductor deviceaccording to example embodiments of the inventive concept will bedescribed. The memory system 1400 may include a memory device 1410 forstoring large amounts of data and a memory controller 1420. The memorycontroller 1420 controls the memory device 1410 so as to read datastored in the memory device 1410 or to write data into the memory device1410 in response to a read/write request of a host 1430. The memorycontroller 1420 may include an address mapping table for mapping anaddress provided from the host 1430 (e.g., a mobile device or a computersystem) into a physical address of the memory device 1410. The memorydevice 1410 may be a semiconductor device according to exampleembodiments of the inventive concept.

FIG. 18 is a graph provided to describe some aspects of the inventiveconcepts. In particular, FIG. 18 is a graph illustrating a dependence ofa magnetic field intensity Hex of the exchange coupling on a thickness Tof the exchange coupling layer, which was obtained from samplesincluding the pinned layer structure PLS described with reference toFIG. 10. A negative Hex means that the system is in theantiferromagnetic coupling state. In this embodiment, the exchangecoupling layer may be formed of iridium (Ir).

Referring to FIG. 18, the exchange coupling intensity Hex of theexchange coupling layer comprising iridium (Ir) had local minimums,e.g., −5500oe, between about 4 Å and about 6 Å and had a local maximum,e.g., −700oe near 11 Å. In other words, when the thickness T of theexchange coupling layer is in a range between about 4 Å and about 6 Å,the exchange coupling intensity Hex had a global minimum. This meansthat, for this embodiment, when the exchange coupling layer has thethickness range of between about 4 Å and about 6 Å, the pinned layerstructure PLS can exhibit a maximized antiferromagnetic coupling effect.It should also be noted, however, that the interaction with the tunnelbarrier layer can further affect the antiferromagnetic coupling effectof the pinned layer structure PLS.

In some embodiments, a magnetic tunnel junction device may include afree layer structure, a pinned layer structure, and a tunnel barrierbetween the free layer structure and the pinned layer structure. Thepinned layer structure may comprise a first magnetic layer having anintrinsic perpendicular magnetization property, a second magnetic layerhaving an intrinsic in-plane magnetization property and extrinsicperpendicular magnetization direction, and an exchange coupling layerinterposed between the first and second magnetic layers. The thicknessof the exchange coupling layer may be greater than 5 Å and less than orequal to 6 Å. Alternatively, the thickness of the exchange couplinglayer may be between about 5 Å and about 6 Å.

The semiconductor memory devices disclosed above may be encapsulatedusing various and diverse packaging techniques. For example, thesemiconductor memory devices according to the aforementioned exampleembodiments may be encapsulated using any one of a package on package(POP) technique, a ball grid arrays (BGAs) technique, a chip scalepackages (CSPs) technique, a plastic leaded chip carrier (PLCC)technique, a plastic dual in-line package (PDIP) technique, a die inwaffle pack technique, a die in wafer form technique, a chip on board(COB) technique, a ceramic dual in-line package (CERDIP) technique, aplastic quad flat package (PQFP) technique, a thin quad flat package(TQFP) technique, a small outline package (SOIC) technique, a shrinksmall outline package (SSOP) technique, a thin small outline package(TSOP) technique, a thin quad flat package (TQFP) technique, a system inpackage (SIP) technique, a multi-chip package (MCP) technique, awafer-level fabricated package (WFP) technique and a wafer-levelprocessed stack package (WSP) technique.

The package in which the semiconductor memory device according to one ofthe above example embodiments is mounted may further include at leastone semiconductor device (e.g., a controller and/or a logic device) thatcontrols the semiconductor memory device.

According to example embodiments of the inventive concept, the freelayer and the second pinned layer may be formed of materials exhibitingan intrinsic in-plane magnetization property. For all that, the freelayer may exhibit a perpendicular magnetization through contact with theperpendicular magnetization inducing layer, and the second pinned layermay exhibit a perpendicular magnetization through an enhancedantiferromagnetic exchange coupling with the first pinned layer that ismade of an intrinsic perpendicular magnetization material. Since thein-plane magnetization materials exhibit the perpendicular magnetizationproperty using external factors, the perpendicular magnetic tunneljunction can have a reduced thickness.

Furthermore, between the first and second pinned layers, there may bethe exchange coupling layer enabling an antiferromagnetic exchangecoupling between the first and second pinned layers. In exampleembodiments, the exchange coupling layer may be formed to have athickness maximizing the antiferromagnetic exchange coupling betweenthat the first and second pinned layers. This enables to reduceeffectively a magnetic interaction between the free and second pinnedlayers.

A single MTJ structures discussed above are only some examples. Theprinciples of the present disclosure may also be applied to spin logicdevices. The spin logic devices may be, for example, all-spin logic(ASL) device and non-volatile spin logic device.

In addition, the inventive concept of the present disclosure may beapplied to the formation of system-on-chip (SOC) devices requiring acache. In such cases, the SOC devices may include a MTJ element formedaccording to the present disclosure coupled to a microprocessor.

Further, the principles of the present disclosure can be applied toother MTJ structures such as dual MTJ structures, where there are tworeference layers with a free layer sandwiched therebetween.

Throughout the specification, features shown in one embodiment may beincorporated in other embodiments within the spirit and scope of theinventive concept.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the present invention. Thus, theappearances of the phrases “in one embodiment” or “in an embodiment” invarious places throughout this specification are not necessarily allreferring to the same embodiment. Furthermore, the particular features,structures, or characteristics may be combined in any suitable manner inone or more embodiments.

As used herein, the term magnetic could include ferromagnetic,ferromagnetic or the like. Thus, the term “magnetic” or “ferromagnetic”includes, for example, ferromagnets and ferrimagnets. Further, as usedherein, “in-plane” is substantially within or parallel to the plane ofone or more of the layers of a magnetic junction. Conversely,“perpendicular” corresponds to a direction that is substantiallyperpendicular to one or more of the layers of the magnetic junction.

Various operations may be described as multiple discrete steps performedin a manner that is most helpful in understanding the invention.However, the order in which the steps are described does not imply thatthe operations are order-dependent or that the order that steps areperformed must be the order in which the steps are presented.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations may be expressly set forth herein for sakeof clarity.

It will be understood by those skilled in the art that, in general,terms used herein, and especially in the appended claims (e.g., bodiesof the appended claims) are generally intended as “open” terms (e.g.,the term “including” should be interpreted as “including but not limitedto,” the term “having” should be interpreted as “having at least,” theterm “includes” should be interpreted as “includes but is not limitedto,” etc.). It will be further understood by those within the art thatif a specific number of an introduced claim recitation is intended, suchan intent will be explicitly recited in the claim, and in the absence ofsuch recitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage of theintroductory phrases “at least one” and “one or more” to introduce claimrecitations. However, the use of such phrases should not be construed toimply that the introduction of a claim recitation by the indefinitearticles “a” or “an” limits any particular claim containing suchintroduced claim recitation to examples containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should be interpreted to mean “at least one”or “one or more”); the same holds true for the use of definite articlesused to introduce claim recitations. Furthermore, in those instanceswhere a convention analogous to “at least one of A, B, or C, etc.” isused, in general such a construction is intended in the sense one havingskill in the art would understand the convention (e.g., “a system havingat least one of A, B, or C” would include but not be limited to systemsthat have A alone, B alone, C alone, A and B together, A and C together,B and C together, and/or A, B, and C together, etc.). It will be furtherunderstood by those within the art that virtually any disjunctive wordand/or phrase presenting two or more alternative terms, whether in thedescription, claims, or drawings, should be understood to contemplatethe possibilities of including one of the terms, either of the terms, orboth terms. For example, the phrase “A or B” will be understood toinclude the possibilities of “A” or “B” or “A and B.”

While example embodiments of the inventive concepts have beenparticularly shown and described, it will be understood by one ofordinary skill in the art that variations in form and detail may be madetherein without departing from the spirit and scope of the attachedclaims.

What is claimed is:
 1. A magnetic tunnel junction device comprising: afree layer structure; a pinned layer structure; and a tunnel barrierbetween the free layer structure and the pinned layer structure, whereinthe pinned layer structure comprises: a first magnetic layer having anintrinsic perpendicular magnetization property; a second magnetic layerhaving an intrinsic in-plane magnetization property and extrinsicperpendicular magnetization direction; and an exchange coupling layerinterposed between the first and second magnetic layers, wherein theexchange coupling layer is iridium, and wherein the exchange couplinglayer has a thickness of about 4 Å to about 6 Å.
 2. The device of claim1, wherein the exchange coupling is antiferromagnetic exchange coupling.3. The device of claim 1, further comprises a non-magnetic metal oxidelayer covering directly the free layer structure.
 4. The device of claim1, wherein the first magnetic layer comprises at least one of: asingle-layer structure made of cobalt-platinum alloy or cobalt-platinumalloy added with an element X, where the element X is at least one ofboron, ruthenium, chromium, tantalum, or oxide; or a multi-layerstructure including cobalt-containing layers and noble metal layersalternatingly stacked on each other, wherein the cobalt-containinglayers are formed of one of cobalt, cobalt iron, cobalt nickel, orcobalt chromium, and the noble metal layers are formed of one ofplatinum and palladium.
 5. The device of claim 1, wherein the secondmagnetic layer is a single- or dual-layered structure including at leastone of Co, CoFeB, CoFeBTa, CoHf, or CoZr.
 6. The device of claim 1,wherein the free layer structure comprises: a free layer having theintrinsic in-plane magnetization property; and a non-magnetic metaloxide layer to induce a perpendicular magnetization property to the freelayer.
 7. The device of claim 6, wherein the free layer is a single- ormulti-layer structure including at least one of Fe, Co, Ni, CoFe, NiFe,NiFeB, CoFeB, CoFeBTa, CoHf, or CoZr.
 8. The device of claim 6, whereinthe non-magnetic metal oxide layer is a single- or multi-layer structureincluding at least one of tantalum oxide, magnesium oxide, rutheniumoxide, iridium oxide, platinum oxide, palladium oxide, or titanium oxideand being in direct contact with the free layer.
 9. A magnetic tunneljunction device comprising: a free layer structure; a pinned layerstructure; and a tunnel barrier between the free layer structure and thepinned layer structure, wherein the pinned layer structure comprises: afirst magnetic layer having an intrinsic perpendicular magnetizationproperty; a second magnetic layer having an intrinsic in-planemagnetization property and extrinsic perpendicular magnetizationdirection; and an exchange coupling layer interposed between the firstand second magnetic layers, wherein a thickness of the exchange couplinglayer is greater than 5 Å and less than or equal to 6 Å.
 10. The deviceof claim 9, wherein the exchange coupling is antiferromagnetic exchangecoupling.
 11. The device of claim 10, wherein the exchange couplinglayer is iridium.
 12. The device of claim 9, further comprises anon-magnetic metal oxide layer covering directly the free layerstructure.
 13. The device of claim 9, wherein the first magnetic layercomprises at least one of: a single-layer structure made ofcobalt-platinum alloy or cobalt-platinum alloy added with an element X,where the element X is at least one of boron, ruthenium, chromium,tantalum, or oxide; or a multi-layer structure includingcobalt-containing layers and noble metal layers alternatingly stacked oneach other, wherein the cobalt-containing layers are formed of one ofcobalt, cobalt iron, cobalt nickel, or cobalt chromium, and the noblemetal layers are formed of one of platinum and palladium.
 14. The deviceof claim 9, wherein the second magnetic layer is a single- ordual-layered structure including at least one of Co, CoFeB, CoFeBTa,CoHf, or CoZr.
 15. The device of claim 9, wherein the free layerstructure comprises: a free layer having the intrinsic in-planemagnetization property; and a non-magnetic metal oxide layer to induce aperpendicular magnetization property to the free layer.
 16. The deviceof claim 15, wherein the free layer is a single- or multi-layerstructure including at least one of Fe, Co, Ni, CoFe, NiFe, NiFeB,CoFeB, CoFeBTa, CoHf, or CoZr.
 17. The device of claim 15, wherein thenon-magnetic metal oxide layer is a single- or multi-layer structureincluding at least one of tantalum oxide, magnesium oxide, rutheniumoxide, iridium oxide, platinum oxide, palladium oxide, or titanium oxideand being in direct contact with the free layer.
 18. A magnetic tunneljunction device comprising: a free layer structure; a pinned layerstructure; and a tunnel barrier between the free layer structure and thepinned layer structure, wherein the pinned layer structure comprises: afirst magnetic layer having an intrinsic perpendicular magnetizationproperty; a second magnetic layer having an intrinsic in-planemagnetization property and extrinsic perpendicular magnetizationdirection; and an exchange coupling layer interposed between the firstand second magnetic layers, wherein a thickness of the exchange couplinglayer is about 5 Å to about 6 Å.
 19. The device of claim 18, wherein theexchange coupling layer comprises iridium (Ir).